Breast biopsy system and methods

ABSTRACT

An apparatus and method are provided for precisely isolating a target lesion in a patient&#39;s body tissue, resulting in a high likelihood of“clean” margins about the lesion when it is removed for diagnosis and/or therapy. This approach advantageously will often result in the ability to both diagnose and treat a malignant lesion with only a single percutaneous procedure, with no follow-up percutaneous or surgical procedure required, while minimizing the risk of migration of possibly cancerous cells from the lesion to surrounding tissue or the bloodstream. In particular, the apparatus comprises a biopsy instrument having a distal end adapted for entry into the patient&#39;s body, a longitudinal shaft, and a cutting element disposed along the shaft. The cutting element is actuatable between a radially retracted position and a radially extended position. Advantageously, the instrument is rotatable about its axis in the radially extended position to isolate a desired tissue specimen from surrounding tissue by defining a peripheral margin about the tissue specimen. Once the tissue specimen is isolated, it may be segmented by further manipulation of the cutting element, after which the tissue segments are preferably individually removed from the patient&#39;s body through a cannula or the like. Alternatively, the specimen may be encapsulated and removed as an intact piece.

FIELD OF THE INVENTION

[0001] The present invention relates to methods and devices for removingtissue samples, and more specifically to improved instruments andmethods for acquiring soft body tissue.

BACKGROUND OF THE INVENTION

[0002] It is often desirable and frequently necessary to sample orremove a portion of tissue from humans and other animals, particularlyin the diagnosis and treatment of patients with cancerous tumors,pre-malignant conditions, and other diseases or disorders.

[0003] Typically, in the case of cancer, particularly cancer of thebreast, there is a great emphasis on early detection and diagnosisthrough the use of screening modalities, such as physical examination,and particularly mammography, which is capable of detecting very smallabnormalities, often nonpalpable. When the physician establishes bymeans of a mammogram or other screening modality, such as ultrasound,that suspicious circumstances exist, a biopsy must be performed tocapture tissue for a definitive diagnosis as to whether the suspiciouslesion is cancerous. Biopsy may be done by an open or percutaneoustechnique. Open biopsy, which is an invasive surgical procedure using ascalpel and involving direct vision of the target area, removes theentire mass (excisional biopsy) or a part of the mass (incisionalbiopsy). Percutaneous biopsy, on the other hand, is usually done with aneedle-like instrument through a relatively small incision, blindly orwith the aid of an artificial imaging device, and may be either a fineneedle aspiration (FNA) or a core biopsy. In FNA biopsy, individualcells or clusters of cells are obtained for cytologic examination andmay be prepared such as in a Papanicolaou smear. In core biopsy, as theterm suggests, a core or fragment of tissue is obtained for histologicexamination which may be done via a frozen section or paraffin section.

[0004] The type of biopsy utilized depends in large part oncircumstances present with respect to the patient, including thelocation of the lesion(s) within the body, and no single procedure isideal for all cases. However, core biopsy is extremely useful in anumber of conditions and is being used more frequently by the medicalprofession.

[0005] A very successful type of image guided percutaneous core breastbiopsy instrument currently available is a vacuum-assisted automaticcore biopsy device. One such successful biopsy device is shown anddisclosed in U.S. Pat. No. 5,526,822 to Burbank et al, expresslyincorporated by reference herein. This device, known commercially as theMAMMOTOME® Biopsy System, which is available from Ethicon Endo-Surgery,Inc., a division of Johnson & Johnson, has the capability to activelycapture tissue prior to cutting the tissue. Active capture allows forsampling through non-homogeneous tissues. The device is comprised of adisposable probe, a motorized drive unit, and an integrated vacuumsource. The probe is made of stainless steel and molded plastic and isdesigned for collection of multiple tissue samples with a singleinsertion of the probe into the breast. The tip of the probe isconfigured with a laterally disposed sampling notch for capturing tissuesamples. Orientation of the sample notch is directed by the physician,who uses a thumbwheel to direct tissue sampling in any direction aboutthe circumference of the probe. A hollow cylindrical cutter severs andtransports tissue samples to a tissue collection chamber for latertesting.

[0006] While this type of system functions very well as a core biopsydevice, there are occasions when it may be useful to have the capabilityof acquiring a relatively large intact tissue sample. One such corebiopsy device is disclosed in U.S. Pat. No. 5,111,828, to Kornberg etal., also expressly incorporated by reference herein. In the devicedisclosed by Kornberg et al., the tissue receiving port is disposed atthe distal end of the device and is oriented axially rather thanlaterally. A disadvantage of this type of device, however, is theinability to acquire a tissue sample having a cross-section larger thanthat of the cannula through which the sample will be removed.Additionally, it is difficult, using such a device, which obtainscylindrical shaped specimens, to determine whether an entire lesion ofinterest is being removed or whether a further procedure will benecessary. This is particularly true because most lesions of interestare typically spherical in shape, having a diameter of approximately 1cm. The only way one can tell whether the entire lesion has been removedusing the Kornberg technique is to remove and examine the specimen,determining whether each of the margins of the specimen is “clean”,meaning that there is no evidence of lesion, or “dirty”, meaning thatlesion is evident right to the edge of the specimen. Of course, if oneor more specimen margins is “dirty”, it is almost a certainty that aportion of the lesion remains in the patient, and if the biopsy testresults on the lesion are positive, a further surgical procedure will beindicated.

[0007] It would be desirable, therefore, to have an apparatus and methodfor isolating a target lesion, with a sufficient border around andbeyond the lesion that the likelihood of “clean” margins is relativelyhigh. It would further be advantageous to have an apparatus and methodavailable for initially isolating the entire target lesion, by cutting aswath completely about the lesion to cut off its blood supply, afterwhich a further procedure is undertaken to remove it from the patient'sbody. This approach would help to minimize the migration of possiblycancerous cells from the lesion to surrounding tissue or bloodstreamduring the removal procedure.

SUMMARY OF THE INVENTION

[0008] The present invention addresses the foregoing problems byproviding such an apparatus and method for precisely isolating a targetlesion, resulting in a high likelihood of“clean” margins. Thisadvantageously will often result in the ability to both diagnose andtreat a malignant lesion with only a single percutaneous procedure, withno follow-up percutaneous or surgical procedure required, whileminimizing the risk of migration of possibly cancerous cells from thelesion to surrounding tissue or the bloodstream.

[0009] More particularly, in one aspect of the invention, a biopsyinstrument is provided for retrieving body tissue, which instrument hasa longitudinal axis. The instrument comprises a distal end adapted forentry into a patient's body, a shaft disposed along the axis, and acutting element disposed along the shaft. The cutting element isactuatable between a radially retracted position and a radially extendedposition. Advantageously, the instrument is rotatable about its axis inthe radially extended position to isolate a desired tissue specimen fromsurrounding tissue by defining a peripheral margin about the tissuespecimen. Once the tissue specimen is isolated, it may be segmented byfurther manipulation of the cutting element, after which the tissuesegments are preferably individually removed from the patient's bodythrough a cannula or the like. Alternatively, the specimen may beencapsulated and removed as an intact piece.

[0010] In another aspect of the invention, an instrument is provided forretrieving body tissue, having a longitudinal axis and comprising adistal end adapted for entry into a patient's body. The instrumentfurther comprises an element for encapsulating a tissue specimen so thatit may be withdrawn as a single unit from the patient's body. Theencapsulating element preferably comprises a plurality of bands disposedalong the instrument axis, each of which are actuatable between aradially retracted position and a radially extended position.

[0011] In yet another aspect of the invention, a method is disclosed forretrieving a tissue specimen from a patient's body, comprising the stepsof inserting an instrument having a distal end, a longitudinal axis, andan axially disposed cutting element, into the patient's body, so that adistal end is disposed in a tissue region from which the tissue specimenis to be taken. The cutting element is radially expanded so that aportion thereof is radially outwardly spaced from the axis of theinstrument. Once the cutting element is radially expanded, it is rotatedabout the axis to cut the tissue and create a peripheral boundary aboutthe tissue specimen, to isolate the tissue specimen from surroundingtissue in the tissue region.

[0012] The invention, together with additional features and advantagesthereof, may best be understood by reference to the followingdescription taken in conjunction with the accompanying illustrativedrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a perspective view of the distal end of one preferredembodiment of the inventive tissue retrieval instrument;

[0014]FIG. 2 is a perspective view illustrating the distal end of amonopolar embodiment of the inventive tissue retrieval instrument shownin FIG. 1;

[0015]FIG. 3 is a perspective view similar to that of FIG. 2,illustrating the distal end of a bipolar embodiment of the inventivetissue retrieval instrument shown in FIG. 1;

[0016]FIG. 4 is a cutaway view from the side illustrating the internalconstruction of a presently preferred proximal drive unit for operatingthe inventive tissue retrieval instrument;

[0017]FIG. 5 is a perspective view from the top illustrating theproximal drive unit of FIG. 4, with the top portion of the housingremoved in order to show portions of its internal construction;

[0018]FIG. 6 is a perspective view from the proximal end illustratingthe proximal drive unit of FIGS. 4 and 5, with the top portion of thehousing removed in order to show portions of its internal construction;

[0019]FIG. 7 is a perspective view from the distal end illustrating theproximal drive unit of FIGS. 4-6, with the top portion of the housingremoved in order to show portions of its internal construction;

[0020]FIG. 8 is a schematic view illustrating the distal end of theinstrument of FIG. 1 disposed in a tissue region from which targettissue is to be retrieved, wherein the distal cutting element isdeployed in a first position for isolating a first segment of a targettissue specimen from surrounding tissue;

[0021]FIG. 9 is a schematic view similar to FIG. 8, wherein the distalcutting element is deployed in a second position for isolating a secondsegment of the target tissue specimen from surrounding tissue;

[0022]FIG. 10 is a schematic view similar to FIGS. 8 and 9, wherein thedistal cutting element is deployed in a third position for isolating athird segment of the target tissue specimen from surrounding tissue;

[0023]FIG. 11 is a perspective view illustrating the distal end of asecond preferred embodiment of the inventive tissue retrievalinstrument;

[0024]FIG. 12 is a perspective cutaway view of the distal end of theembodiment of FIG. 11, illustrating the internal construction thereof,including tissue wrapping and cutting elements in their stored position;

[0025]FIG. 13 is a perspective cutaway view similar to that of FIG. 12,wherein the sheath has been retracted in order to deploy the tissuewrapping and cutting elements shown in FIG. 12;

[0026]FIG. 14 is a side schematic view of the distal end of theembodiment of FIGS. 11-13, illustrating the deployment of the tissuewrapping and cutting elements shown in FIG. 12;

[0027]FIG. 15 is a perspective view illustrating the tissue wrapping andcutting elements of FIGS. 12 and 14 in their fully deployed position;

[0028]FIG. 16 is a side view showing the deployed tissue wrapping andcutting elements after the distal end of the instrument has been rotatedto twist the wrapping and cutting elements in order to wrap a targettissue sample;

[0029]FIG. 17 is a perspective, schematic view of an alternativeembodiment of the distal end of the inventive tissue retrievalinstrument, wherein the cutting element of the instrument is in aretracted position;

[0030]FIG. 18 is a perspective, schematic view similar to FIG. 17,illustrating the cutting element in a deployed position for creatingcylindrical tissue segments; and

[0031]FIG. 19 is a perspective, schematic view similar to FIGS. 17 and18, illustrating the cutting element in a deployed position for creatingtissue segments of varying heights.

DESCRIPTION OF THE INVENTION

[0032] Referring now more particularly to FIG. 1, there is shown thedistal end 12 of a first preferred embodiment of an inventive tissueretrieval or biopsy instrument 10. The distal end 12 preferablycomprises a disposable wand portion, including a distal tip 14. The tip14 may comprise a conventional trocar tip, or, preferably, may includean electrosurgical (RF) element or wire 16 which may be energized by aconventional electrosurgical generator (not shown) in order tofacilitate tissue cutting and consequent advancement of the instrument10 to a predetermined tissue site in the patient's body.

[0033] Proximally of the tip 14 is a shaft 18, preferably lying along anaxis 19 (FIG. 1) of the instrument, on which is disposed a cuttingelement or wire 20. This wire 20 is disposed axially along the length ofthe shaft 18 in its retracted position (not shown), but may be deployedradially outwardly, as shown in FIG. 1. The element 20 is preferablycomprised of a wire or rectangular band fabricated of memory metal suchas Nitinol, though stainless steel, tungsten, or other biocompatiblematerials could also be employed, if desired. The cutting element 20acts as an electrosurgical cutter, energizable by means of RF energyprovided by the electrosurgical generator discussed supra. Theinstrument 10 may be monopolar, as illustrated in FIG. 2, with thecutting element 20 comprising the active electrode and a returnelectrode spaced from the instrument 10 and most typically beingdisposed on the patient's skin in the form of a patch electrode on thethigh or back. Alternatively, the instrument 10 may preferably bebipolar, as illustrated in FIG. 3, with the cutting element comprisingthe active electrode and a return electrode 22 being disposed on theinstrument in close proximity to the active electrode, such as along theshaft 18. With such an arrangement, a layer of insulation 23 is disposedbetween the return electrode (comprising a major portion of the surfacearea of the shaft 18) and the portion of the shaft adjacent to theactive electrode, which receives the cutting element 20 in its retractedposition. The bipolar embodiment is generally preferred because of agreater safety factor and lower power requirements.

[0034] A plurality of cutting wires 20 may be employed if desired,preferably spaced circumferentially about the shaft 18. In someembodiments, it may be preferably to have webs between the cuttingelements, to create a“sail” rather than entire distinct separate cuttingelements.

[0035] Referring now more particularly to FIGS. 4-7, a proximal reusabledriver portion 24 for the distal end or disposable wand portion 12 isshown. The driver portion 24 is preferably disposed on a stereotacticrail 26, in known fashion, for guidance of the instrument 10 to apredetermined tissue site using known imaging techniques. Suchstereotactic imaging systems are available, for example, from Fischer,Inc. or Lorad, Inc. Alternative imaging systems, such as mammographic,ultrasonic, CT, MRI guidance systems may be used in place of astereotactic system, if desired. Additionally, the instrument may beguided to the lesion site using an articulating arm system or manually,rather than on a stereotactic rail.

[0036] The reusable driver portion 24 comprises a housing 28 withinwhich is disposed a coaxial arrangement comprising an outer sheath 30,the shaft 18, and a rod 32 which is attached at its distal end to thecutter element 20. A knob 34 is rotatably attached to the shaft 18through a gearing system 35 to rotate the shaft 18 as desired, for thepurpose of circumferentially orienting and rotating the cutting element20. Three levers 36, 38, and 40 extend outwardly through slots 42, 44,and 46, respectively, in the side of the housing 28. The first lever 36is actuatable to slide the sheath 30 axially both proximally anddistally, for a purpose to be described hereinbelow. The second lever 38is actuatable to move the shaft 18 axially in distal and proximaldirections, as desired. The third lever 40 is actuatable to move the rod32 axially in distal and proximal directions, as desired. Since the rod32 is attached at its distal end to the proximal end of the wire cutter20, movement of the rod 32 in an axial direction also causes theproximal end of the wire cutter 20 to move in an axial direction. Sincethe distal end of the cutter 20 is anchored to the shaft 18, movement ofthe proximal end of the cutter element 20 in a distal direction causesthe midportion of the cutting element 20 to bow radially outwardly to aradially expanded position, as shown in any of FIGS. 1-3, while movementof the proximal end of the cutter element 20 in a proximal directioncauses the midportion of the cutter element 20 to retract radially toits stowed position, disposed linearly along the axial length of theshaft 18, preferably within a recess 48 (FIG. 1).

[0037] An advantageous feature of the invention is the employment of aseries of stops 50 in the second slot 44, and a series of stops 52 inthe third slot 46, as illustrated in FIGS. 5-7. The stops 50 enable thesecond lever 38 to be actuated to a plurality of discrete axialpositions, which in turn permits the shaft 18 to be actuated togacorresponding plurality of discrete axial positions for fine tuning theaxial position of the electrosurgical cutting element 20. Similarly, thestops 52 enable the third lever 40 to be actuated to a plurality ofdiscrete axial positions, which in turn permits the electrosurgicalcutting element 20 to be radially extended to a corresponding pluralityof radially extended positions, for a purpose to be described more fullyhereinbelow.

[0038] With reference now more particularly to FIGS. 8-10, the operationof the first preferred embodiment of the inventive device will beexplained. Initially, when it is determined that either a diagnostic ortherapeutic biopsy procedure is indicated, the distal disposable wandportion 12 of the instrument 10 will be moved axially to a positionwherein the distal tip is adjacent to and preferably within a targetlesion 54, using the stereotactic rail 26 and associated imaging system.During this process step, wherein gross linear movement of the wand 12is controlled by the rail system 26, the electrosurgical cutting element16 on the distal tip 14 is energized to pierce and cut through thepatient's body tissue 56 to permit distal advancement of the wand 12 tothe region surrounding the lesion 54.

[0039] Once the distal tip 14 is generally in the desired positionadjacent to or within the target lesion 54, using the stereotactic rail26, the second lever 38 is actuated to provide fine tuning of the axialposition of the distal tip 14 relative to the lesion 54, by moving theshaft 18 axially to a desired position, and securing the lever 38 in anappropriate stop 50 to maintain the desired axial position. This fineaxial adjustment of the axial movement of the shaft 18 is performedusing appropriate imaging equipment. The objective of this process stepis to ensure that the distal end of the cutting wire 20 is disposeddistally of the distal peripheral edge of the lesion 54, while at thesame time the proximal end of the cutting wire 20 is disposed proximallyof the proximal peripheral edge of the lesion 54. This will ensure theability to isolate the entire lesion 54 during the cutting procedure,with sufficient margins to minimize the chance that any portion of thelesion inadvertently remains behind in the patient's body followingremoval thereof.

[0040] When the distal tip 14 is in the precise position desired by thepractitioner, first lever 36, which is normally disposed in a firstdetent 58 (FIGS. 5 and 6) in the first slot 42, is actuated proximallyuntil it rests in a second detent 60 (FIG. 5) in the first slot 42. Thisaction retracts the sheath 30 proximally a sufficient distance topartially uncover the cutting element 20. It should be noted, however,that in some circumstances it may be desirable to fully retract thesheath, so that the entire cutting element 20 is released, in order tocreate a different cutting geometry. In such an instance, a detent 61(FIG. 7) is provided within the slot 42 to accommodate the lever 36 inthe fully proximal position necessary to achieve full axial retractionof the sheath. Additional intermediate detents 60 (not shown) may beprovided to retract the sheath to intermediate positions correspondingto various partial radial extension positions of the cutting element.

[0041] After the sheath 30 is retracted as desired, the third lever 40may then be actuated distally along the third slot 46 to an intermediatestop 52, thereby causing the rod 32, and therefore the proximal end ofthe cutting element 20, to move axially a distance equivalent to thattraversed by the lever 40. This, of course, results in the partialradial expansion of the cutting element 20 to an arched or bowedconfiguration as shown in FIG. 8. The extended configuration of thecutting element 20 may define, when rotated about the instrument axis, aspherical cutting volume, as shown, or it may be configured to define anelliptical or toroidal cutting volume when the cutting element isrotated about the instrument axis 19, rather than a spherical volume.

[0042] Of course many other mechanisms for radially expanding thecutting element 20 may be utilized as well, within the scope of theinvention. For example, since the wire 20 is preferably fabricated of ashaped memory or superelastic material, the proximal retraction of thesheath 30, and resultant release of the wire 20, may be sufficient tocause the cutting wire 20 to radially expand to its desired position.

[0043] Once the cutting element 20 is partially radially expanded asdescribed supra, an inner portion of the target lesion 54 is isolatedfrom surrounding tissue. To complete this step, the cutting element 20is energized by the electrosurgical generator (not shown), after whichthe knob 34 is rotated, either manually or via a motorized drivemechanism, to rotate the cutting element 20 through a 360 degree arc.This rotational cutting action functions to completely sever the innerportion of the tissue sample from the surrounding tissue, therebycutting off all blood supply to the inner tissue sample. Alternatively,if desired, the cutting element 20 may be simultaneously rotated andmoved axially, by moving the shaft 18 axially, in order to createa“corkscrew” - shaped tissue segment.

[0044] Once this initial isolation step is completed, the cuttingelement or wire 20 is preferably further radially extended to theposition shown in FIG. 9. This is accomplished by sliding the lever 36proximally to another detent 60 to further proximally retract the sheath30. Then, the third lever 40 may be axially slid distally to anotherstop or detent 52 to further radially extend the cutting wire 20. Onceradially positioned, the cutting element 20 is energized by theelectrosurgical generator, after which the knob 34 is rotated to rotatethe cutting element 20 through a 360 degree arc. This rotational cuttingaction functions to completely sever a second segment of the tissuesample from the surrounding tissue, thereby cutting off all blood supplyto this segment as well.

[0045] These steps may be repeated as many times as desired, in order toensure that the tissue sample is segmented for efficient removal fromthe patient's body. Ultimately, however, a final cut is preferably made,by fully retracting the outer sheath 30, using the slide lever 36, andfully extending the cutting wire 20, using the slide lever 40, so thatthe cutting element 20 extends radially beyond the periphery of thetarget lesion 54, as illustrated in FIG. 10. The cutting element is thenenergized with RF energy, in the same manner as previously, after whichthe knob 34 is rotated to rotate the cutting wire 20 through a completearc about the axis 19. At this point, the entire lesion 54 should becompletely isolated from surrounding tissue, with a sufficient marginabout the outer periphery thereof to ensure successful removal of theentire lesion.

[0046] During the foregoing segmentation process, if the cutting element20 remains charged by RF energy during the stepwise radial extensionprocess, the outer tissue rings will be further segmented radially.

[0047] Other segmentation approaches may be advantageously utilized aswell, if desired. For example, rather than segmenting the tissue samplecircumferentially, from the inside out, the tissue sample may besegmented circumferentially from the outside in, i.e. by making an outercircumferential cut (FIG. 10), then partially retracting the cuttingelement 20 and cutting additional layers, as shown in FIGS. 8 and 9.Alternatively, the tissue may be sectioned by extending and retractingthe cutting element 20 radially, akin to“sectioning an orange”.Additional radially oriented cutting elements could be employed as wellto further segment the tissue.

[0048] An alternative approach to segmenting the tissue specimen to beretrieved is illustrated in the embodiment shown in FIGS. 17-19. In thisembodiment, wherein like elements to those in the embodiment of FIG. 1are designated by like reference numerals, succeeded by the letter a,there is shown a tissue retrieval or biopsy instrument 10 a, having adistal tip 14 a with an electrosurgical element or wire 16 a for cuttingtissue and thereby permitting advancement of the instrument into apatient's body. A shaft or cannula 18 a is disposed along an axis 19 aof the instrument. A longitudinal slot 66 is disposed axially along aportion of the length of the cannula 18 a. A cutting element or wire 20a, which is preferably an electrosurgical cutting element, is disposedso as to be extendable from and retractable into the slot. The cuttingelement is shown in a retracted position in FIG. 17, and in an extendedposition in FIGS. 18 and 19.

[0049] In operation, once the instrument 10 a has been positioned sothat the distal tip is adjacent to a lesion to be removed, in the mannerdescribed supra with respect to the embodiment of FIG. 1, the cuttingelement 20 a is charged with RF energy from a proximally disposedelectrosurgical generator (not shown). Then, the cutting element 20 a isradially extended by the practitioner, using a proximal controlmechanism (not shown), to a position as shown, for example, in FIG. 18.Once extended, the cutting element is moved axially in a proximaldirection along the slot 66, as illustrated by the arrow 68 and thephantom images of the cutting element 20 a, in order to isolate agenerally cylindrical tissue segment, as the cannula 18 a is rotatedabout its axis 19 a simultaneously.

[0050]FIG. 19 illustrates a procedure similar to that illustrated inFIG. 18, except that while the cutting element 20 a is being axiallymoved in a proximal direction as shown by arrows 70, it is also deployedto various radial heights, in order to create a variable height cut.

[0051] Once segmentation of the tissue sample has been completed,whichever embodiment has been employed, each tissue segment can bewithdrawn using a suitable retrieval apparatus. Preferably, the tissuesegments are withdrawn through a cannula, such as the sheath 30, usingsuch means as a suction grasper, flexible mechanical graspers, an augerconveyor, a prickly bristle or brush grasper, a wire retrieval basket,or the like.

[0052] The foregoing procedure and apparatus may be used for either adiagnostic or a therapeutic purpose. It is particularly advantageous fora diagnostic procedure because the resultant incision from the procedurewill not substantially exceed in length the diameter of the cannula. Onthe other hand, a second preferred embodiment, illustrated in FIGS.11-16, is particularly suited to a therapeutic procedure, wherein it ishighly desired to ensure that the entire lesion of interest is removedin one step, without segmenting that lesion within the body. Thisapproach emphasizes maximum safety, in that only a single procedure isnecessary, assuming the tissue sample margins are clean, and theincision necessary to remove the intact tissue sample is of the minimumsize necessary to remove the sample. With this procedure, there is alsoa somewhat reduced risk of cell migration from the specimen to thesurrounding tissue, since as described below, the specimen isencapsulated as soon as it is isolated and then promptly removed. Nosegmentation of the specimen occurs within the patient's body.

[0053] Referring now to FIGS. 11-14, wherein like elements to those inthe first embodiment are identified by like reference numerals, followedby the letter“b”, there is shown the distal end or disposable wandportion 12 b of an instrument 10 b. The portion 12 b includes a distaltip 14 b, which may be constructed in a manner similar to that of tip 14in FIG. 1, a shaft 18 b, and a sleeve 30 b. Disposed in a radiallyretracted orientation in a recess 48 b of the shaft 18 b are a pluralityof encapsulation elements or bands 72, one of which also comprises asingle electrosurgical cutting element 20 b. For the purposes of theinvention it is unimportant which of the encapsulation elements 72 maybe charged by means of RF energy to form an electrosurgical cutter, andin certain instances it may be advantageous to employ a plurality ofcutting elements. Each of the encapsulation elements 72 and the cuttingelement 20 b are attached at their distal ends to the distal end of theshaft 18 b, at its connection with the distal tip 14 b of the instrument10 b, which connection is preferably accomplished by means of a keyway74.

[0054] The proximal end of the instrument 10b may be substantially thesame as that for the instrument 10, illustrated in FIGS. 4-7, comprisinga reusable driver portion having an actuator for axially moving thesheath 30 b between proximal and distal positions, a linear actuator foraxially moving the shaft 18 b, an actuator for rotationally moving theshaft 18 b, and an actuator for axially moving the proximal ends of theencapsulation elements 72 and cutting element 20 b, in order to radiallyextend and retract each of the elements 72 and 20 b, as illustrated inFIGS. 14-16.

[0055] In operation, as with the first embodiment of FIG. 1, when it isdetermined that either a diagnostic or therapeutic biopsy procedure isindicated, the distal disposable wand portion 12 b of the instrument 10b will be moved axially to a position wherein the distal tip is adjacentto and distally of a target lesion, using the stereotactic rail 26 andassociated imaging system. During this process step, wherein grosslinear movement of the wand 12 b is controlled by the rail system 26,the electrosurgical cutting element (not shown) on the distal tip 14 bis energized to pierce and cut through the patient's body tissue topermit distal advancement of the wand 12 b to the region surrounding thelesion.

[0056] Once the distal tip 14 b is generally in the desired positionadjacent to the target lesion, using the stereotactic rail 26, thesecond lever 38 is actuated to provide fine tuning of the axial positionof the distal tip 14 b relative to the lesion, by moving the shaft 18 baxially to a desired position, and securing the lever 38 in anappropriate stop 50 to maintain the desired axial position. This fineaxial adjustment of the axial movement of the shaft 18 b is performedusing appropriate imaging equipment. The objective of this process stepis to ensure that the distal end of the cutting wire 20 b is disposeddistally of the distal peripheral edge of the lesion, while at the sametime the proximal end of the cutting wire 20 b is disposed proximally ofthe proximal peripheral edge of the lesion. This will ensure the abilityto isolate the entire lesion during the cutting procedure, withsufficient margins to minimize the chance that any portion of the lesioninadvertently remains behind in the patient's body following removalthereof.

[0057] When the distal tip 14 b is in the precise position desired bythe practitioner, first lever 36, which is normally disposed in a firstdetent 58 (FIGS. 5 and 6) in the first slot 42, is actuated proximallyuntil it rests in a second detent 60 (FIG. 7) in the first slot 42. Thisaction retracts the sheath 30 b proximally a sufficient distance tocompletely uncover the cutting element 20 b and associated encapsulationelements 72. The third lever 40 may then be actuated distally along thethird slot 46 to the distal-most stop 52, thereby causing the rod 32,and therefore the proximal ends of the cutting element 20 a andencapsulation elements 72, to move axially a distance equivalent to thattraversed by the lever 40. This, of course, results in the radialexpansion of the cutting element 20 b and encapsulation elements 72 toan arched or bowed configuration as shown in FIG. 14, wherein thecutting element 20 b defines a peripheral boundary which lies radiallybeyond the peripheral boundary of the lesion, as in the case of thefirst embodiment shown in FIG. 8. Again, it should be noted that thecutting element and encapsulation elements need not be fully extended,especially if an ellipsoidal or toroidal cutting geometry is desired, inwhich case intermediate stop 61 is utilized.

[0058] Once the cutting element 20 b and associated encapsulationelements 72 are radially expanded as described supra, it is time toisolate the target lesion from surrounding tissue. Advantageously, aspherical or toroidal tissue sample having a radius of at least 15 mmmay be defined and isolated by rotating the cutting element 20 b aboutthe axis of the shaft 18 b. The encapsulation elements 72 will also berotated during this process, but their function is not yet important. Tocomplete the isolation step, the cutting element 20 b is energized bythe electrosurgical generator (not shown), after which the knob 34 isrotated, either manually or via a motorized drive mechanism, to rotatethe shaft 18 b, and thus the cutting element 20 b through a 360 degreearc. This rotational cutting action functions to completely sever thetissue sample from the surrounding tissue, thereby cutting off all bloodsupply to the tissue sample (and thus from the lesion, which should becompletely contained within the tissue sample).

[0059] After the isolation step is completed, the isolated tissue samplemay be retrieved from the patient's body 56. This retrieval step may beaccomplished in a number of ways, but it is the objective in connectionwith the illustrated embodiment to encapsulate and remove the isolatedtissue sample in one piece. Accordingly, as is illustrated in FIGS. 15and 16, continued rotation of the shaft 18 b, once the isolation stephas been completed, preferably with the cutting element 20 bde-energized, will twist and tighten the encapsulating elements 72 andthe cutting element 20 b about the tissue sample (not shown). As theshaft 18 b is rotated, and the encapsulating elements 72 radiallyretracted and twisted, they will function to deform the tissue sampleradially so that it is more compact and more securely retained withinthe spaced defined by the encapsulating elements 72.

[0060] Once the tissue sample has been fully encapsulated, the tissuesample may be removed from the patient's body. Advantageously, since thetissue sample is larger in cross-section than the cross-section of thesheath 30 b, the inventors have developed an inventive approach forremoval thereof which results in minimum trauma and incision size forthe patient while still permitting the removal of an intact specimen. Toremove the specimen, the sheath 30 b is retracted proximally, followingwhich the cutting element 20 b is again energized by the electrosurgicalgenerator. The shaft 18 b, with the tissue specimen encapsulatedthereabout, is then proximally withdrawn by the practitioner, with thecutting element 20 b functioning to cut through the tissue necessary tocreate a passage for exit of the sample. Once the unit, including theshaft and encapsulated tissue mass, is completely withdrawn from thebody, the incision created by the cutting element 20 b upon withdrawalfrom the body may be adhesively closed, with minimal required follow-upcare and scarring.

[0061] Many alternative embodiments may be used to accomplish the methodoutlined supra, which essentially involves isolating the tissue massfrom surrounding tissue, encapsulating the tissue mass in place about ashaft, then removing the encapsulated tissue mass and shaft from thebody by energizing an RF electrosurgical cutter to cut its way out,without the need for a cannula or pre-existing incision. For example, aplurality of cutting elements could be employed, or a separate cuttingelement could be disposed on the shaft. An important aspect of theinvention, of course, is a relatively high likelihood of acquiring theentire lesion of interest in a single therapeutic procedure, without theneed for follow-up surgery.

[0062] While this invention has been described with respect to variousspecific examples and embodiments, it is to be understood that theinvention is not limited thereto and that it can be variously practicedwithin the scope of the following claims.

What is claimed is:
 1. A biopsy instrument for retrieving body tissue,having a longitudinal axis and comprising: a distal end adapted forentry into a patient's body; and a cutting element disposed on saidinstrument, said cutting element being actuatable between a radiallyretracted position and a radially extended position, relative to saidaxis, and being movable in said radially extended position to isolate adesired tissue specimen from surrounding tissue by defining a peripheralmargin about said tissue specimen.
 2. The biopsy instrument as recitedin claim 1, wherein said cutting element is rotatable about said axis insaid radially extended position to isolate said desired tissue specimen.3. The biopsy instrument as recited in claim 1, wherein said cuttingelement is movable axially in said radially extended position to isolatesaid desired tissue specimen.
 4. The biopsy instrument as recited inclaim 1, said distal end comprising an electrosurgical cutting elementfor cutting tissue and facilitating advancement of said instrument intothe patient's body.
 5. The biopsy instrument as recited in claim 2, andfurther comprising a shaft disposed along said axis.
 6. The biopsyinstrument as recited in claim 5, wherein said cutting element comprisesan electrosurgical cutting element.
 7. The biopsy instrument as recitedin claim 5, said instrument comprising a monopolar instrument whereinthe electrosurgical cutting element comprises an active electrodethereof.
 8. The biopsy instrument as recited in claim 5, said instrumentcomprising a bipolar instrument wherein the electrosurgical cuttingelement comprises an active electrode thereof.
 9. The biopsy instrumentas recited in claim 8, wherein a portion of said shaft comprises areturn electrode of the bipolar instrument.
 10. The biopsy instrument asrecited in claim 5, and further comprising a sheath which is axiallymovable between distal and proximal positions for selectively coveringand uncovering the cutting element.
 11. The biopsy instrument as recitedin claim 10, and further comprising a proximal driver unit forcontrolling radial expansion and retraction of said cutting element androtation of said cutting element about said axis.
 12. The biopsyinstrument as recited in claim 11, wherein the proximal driver unitfurther controls axial movement of said shaft and axial movement of saidsheath.
 13. The biopsy instrument as recited in claim 5, wherein saidcutting element may be manipulated to segment said tissue specimen afterit has been isolated from the surrounding tissue.
 14. The biopsyinstrument as recited in claim 13, wherein said cutting element segmentssaid tissue specimen as it is being retracted from said radiallyextended position to said radially retracted position.
 15. The biopsyinstrument as recited in claim 14, wherein said radially extendedposition comprises a first radially extended position, and said cuttingelement is further actuatable to a plurality of additional radiallyextended positions, said cutting element being rotatable about said axisin each of said radially extended positions to selectively peripherallysegment said tissue specimen.
 16. The biopsy instrument as recited inclaim 13, and further comprising a cannula having a lumen for providinga passageway into the patient's body, the segments of said tissuespecimen being removable from the patient's body through said cannula.17. The biopsy instrument as recited in claim 5, wherein said instrumentfurther comprises an element for encapsulating said tissue specimen sothat it may be withdrawn as a single unit from the patient's body. 18.The biopsy instrument as recited in claim 17, wherein said encapsulatingelement comprises a band disposed along said shaft, said band beingactuatable between a radially retracted position and a radially extendedposition.
 19. The biopsy instrument as recited in claim 17, wherein saidencapsulating element comprises a plurality of bands disposed along saidshaft, each of said bands being actuatable between a radially retractedposition and a radially extended position.
 20. The biopsy instrument asrecited in claim 19, wherein said cutting element comprises one of saidencapsulating elements.
 21. An instrument for retrieving body tissue,having a longitudinal axis and comprising: a distal end adapted forentry into a patient's body; and an element for encapsulating a tissuespecimen so that it may be withdrawn as a single unit from the patient'sbody.
 22. The instrument as recited in claim 21, wherein saidencapsulating element comprises an axially disposed band, said bandbeing actuatable between a radially retracted position and a radiallyextended position.
 23. The biopsy instrument as recited in claim 21,wherein said encapsulating element comprises a plurality of bandsdisposed along said axis, each of said bands being actuatable between aradially retracted position and a radially extended position.
 24. Thebiopsy instrument as recited in claim 23, wherein said instrument isrotatable about said axis in order that said bands may be twisted forencapsulating said tissue specimen.
 25. The biopsy instrument as recitedin claim 21, and further comprising an axially disposed cutting element,the cutting element being actuatable between a radially retractedposition and a radially extended position, and being rotatable aboutsaid axis in said radially extended position to isolate a desired tissuespecimen from surrounding tissue by defining a peripheral margin aboutsaid tissue specimen.
 26. The biopsy instrument as recited in claim 25,wherein said cutting element comprises an electrosurgical cuttingelement.
 27. The biopsy instrument as recited in claim 21, and furthercomprising a sheath which is axially movable between distal and proximalpositions for selectively covering and uncovering the encapsulatingelement.
 28. The biopsy instrument as recited in claim 21, and furthercomprising a cutting element which is actuatable to cut tissue as saidinstrument is proximally withdrawn from said patient's body with saidencapsulated intact tissue specimen.
 29. A method for retrieving atissue specimen from a patient's body, comprising the steps of:inserting an instrument having a distal end, a longitudinal axis, and anaxially disposed cutting element into the patient's body, so that thedistal end is disposed in a tissue region from which the tissue specimenis to be taken; radially extending said cutting element so that aportion thereof is radially outwardly spaced from the axis of saidinstrument; and rotating said cutting element about said axis to cutsaid tissue and create a peripheral boundary about said tissue specimen,to isolate the tissue specimen from surrounding tissue in the tissueregion.
 30. The method as recited in claim 29, and further comprisingthe step of encapsulating said tissue specimen.
 31. The method asrecited in claim 30, wherein the encapsulating step includes the step ofradially expanding at least one encapsulating element so that a portionthereof is radially outwardly spaced from the axis of said instrumentand rotating said instrument about its axis so that said at least oneencapsulating element encloses said tissue specimen.
 32. The method asrecited in claim 31, wherein said at least one encapsulating elementcomprises a plurality of bands which are disposed axially along saidinstrument.
 33. The method as recited in claim 30, and furthercomprising the step of proximally withdrawing said instrument, with theencapsulated tissue specimen, from the patient's body, said stepincluding the step of cutting tissue as the instrument is withdrawn. 34.The method as recited in claim 29, and further comprising the step ofsegmenting said tissue specimen.
 35. The method as recited in claim 34,and further comprising the step of withdrawing each segment of saidtissue specimen through a cannula lumen.
 36. The method as recited inclaim 34, wherein the step of segmenting said tissue specimen includesthe step of radially retracting said cutting element so that the tissuespecimen is segmented radially.
 37. The method as recited in claim 34,wherein the step of segmenting said tissue specimen includes the stepsof partially radially retracting said cutting element from its fullyradially expanded position and rotating the instrument about its axis tocut said tissue and create a circumferential tissue segment.
 38. Themethod as recited in claim 37, wherein the segmenting step is repeatedat differing partially radially expanded positions of the cuttingelement, so that a plurality of circumferential tissue segments arecreated.
 39. The method as recited in claim 29, and further comprisingthe step of simultaneously moving the cutting element axially as it isrotated about said axis to cut said tissue.